Paging receivers sometimes include the capability to scan a number of frequency channels to locate a channel carrying the desired paging data. In simple pagers, the receiver simply tunes every channel in the paging spectrum until it finds a channel carrying the desired paging data. In more advanced systems, each paging transmitter may broadcast a list of alternative paging channels that are used in the area surrounding the transmitter. On finding one such station, a paging receiver is provided a small local list of other stations that it can examine for data if the original station is lost, obviating the need to scan the entire frequency spectrum. Such a system is disclosed in application Ser. No. 367,727 filed simultaneously herewith and entitled Paging System With Local Channel Lists.
The scanning process is energy intensive and reduces the battery life available for the more productive task of receiving pages. If a pager that relies on a local channel list is moved from the geographical area to which the list relates, the pager may exhaust its battery vainly searching for paging signals where there are none.
It is an object of the present invention to overcome this problem.
It is a more particular object of the present invention to search through successively less likely channels at successively slower rates to locate a channel carrying paging data.